Browse Articles

Étendue and radiance conservation in transformation optics establish strict analytical bounds on field enhancement

Multi-metric comparative evaluation of DeepSeek and ChatGPT in USMLE versus CNMLE for medical education

Diverse and rare candidate MODY gene variants were identified in one-fifth of a Bangladeshi cohort with nonobese, nonautoimmune youth-onset diabetes

CHD1L promotes testicular cancer progression through epigenetic activation of the CXCR6/PI3K/AKT pathway

Asymmetric Electrolytes Govern Tetrahydroxozincate Dynamics for Stable Alkaline Zinc Batteries

ABSTRACT Green electrochemical energy storage is essential for carbon neutrality, and alkaline zinc batteries offer a compelling solution due to their inherent safety, low cost, and high energy density. However, their performance is limited by parasitic reactions, including corrosion, gas evolution, and slow Zn/ZnO conversion kinetics stemming from inefficient dissociation of the tetrahydroxozincate [Zn(OH) 4 2− ] intermediate. We address this by designing a series of cobalt porphyrins (Co‐4N, Co‐3N‐O, Co‐3N‐S) that modulate the metal center's charge density for accelerating Zn(OH) 4 2 − decomposition, and control Zn 2 + transport through the carboxyl‐functionalized peripheries. The Co‐3N‐O‐modified electrolyte achieves exceptional stability, maintaining stable cycle for over 80,000 s at 5 mA cm − 2 , which is more than four times longer than the <20,000 s achieved by the conventional KOH + ZnO electrolyte. In Zn||Ni batteries, this molecularly engineered electrolyte enables 110 stable cycles at 1 mA cm −2 , significantly outperforming the unmodified system, which sustained only 20 cycles. These findings elucidate a structure‐kinetics relationship for zincate regulation and demonstrate how customized molecular asymmetry can overcome persistent challenges in aqueous battery chemistry, offering a pathway to high‐performance, durable energy storage systems.

Weyl semimetal engineering by symmetry control in NiTe2

In this work, we investigate the emergence of Weyl points in an inversion symmetry-breaking 1T-NiTe2 system. Through first-principles calculations based on the density functional theory combined with tight-binding methods, we find three distinct sets of Weyl crossings under an appropriate symmetry breaking. The first set, composed of four Weyl points, emerges from the Dirac semimetal. Surprisingly, the other two sets result in additional 24 Weyl crossings, depending on the weight of the symmetry breaking. We investigate the topological characteristics of the Weyl semimetals by computing the Weyl chirality, Berry curvature, and the evolution of Wannier charge centers. Additionally, the bulk-boundary correspondence has been shown by computing the Fermi arcs. Our results provide a way for creating and manipulating distinct sets of Weyl points with appropriate external control, which can provide a valuable guide to design Weyl crossings in materials for applications in the Weyltronics field.

Tuning Redox Behavior of Pyrene–Benzothiadiazole/TTF–Based Covalent Organic Framework Electrodes in Dual‐Ion Batteries

ABSTRACT Covalent organic frameworks (COFs) have emerged as promising electrode materials for secondary‐ion batteries, where redox‐active building blocks and linkages enable tunable redox properties, while ordered pores serve as nanochannels for fast ion transport. We report a novel highly crystalline 2D PyTTF‐COF, synthesized by integrating n ‐type pyrene–benzothiadiazole (PyBT) and p ‐type tetrathiafulvalene (TTF) subunits via an n ‐type imine linkage, yielding a bipolar electrode capable of reversible 16 e − dual cation–anion storage. Initially, the dual‐ion, redox synergy was tested in a Li‐ion half‐cell, where PyTTF served as cathode, and 1 м LiPF 6 or LiTFSI electrolytes were employed to probe anion‐dependent electrochemical behavior. Electrochemical evaluation in Li‐ion half cells revealed a wide electrochemical window of 0.1−3.6 V vs. Li/Li + , with markedly enhanced charge‐storage kinetics and ion diffusion with LiTFSI relative to LiPF 6 electrolytes. The PyTTF electrode delivered specific capacities of 286 mAh g −1 (LiTFSI) and 184 mAh g −1 (LiPF 6 ) at 0.3 A g −1 , highlighting the strong influence of anion identity. Systematic variation of LiTFSI salt concentration (1−3 м) revealed strong correlations between electrolyte composition, ion storage dynamics, and interfacial charge‐transfer resistance. This study highlights, for the first time, the critical importance of tailoring both charge‐carrier identity and electrolyte concentration to unlock the full potential of bipolar COF electrodes for dual‐ion batteries.

Anomalous tip-sample distance behavior on the tip-enhanced Raman spectroscopy of graphene in ambient conditions

Tip-enhanced Raman spectroscopy (TERS) combines Raman spectroscopy with scanning probe microscopy to overcome the spatial resolution limitation imposed by light diffraction, offering a primary optical technique for the comprehensive study of two-dimensional (2D) materials. In this work, we investigate an anomalous decay profile of the TERS intensity of the graphene 2D band as the tip-sample separation changes, observations enabled by high TERS efficiency and accuracy in tip-approach and tip-retract procedures. The anomalous results can be properly described by the addition of an ad hoc deformation to the effective tip-sample distance, rationalized here as due to the presence of a liquid meniscus formed via capillary forces.

Surface‐State–Regulated Product Distribution in Photothermal CO ₂ Hydrogenation Over MXene‐Based S‐Scheme Catalyst

ABSTRACT The rational design of heterostructured photocatalysts that simultaneously enable efficient carrier separation, photothermal synergy, and controllable reaction pathways is crucial for advancing CO 2 conversion. Here, a Ni/Ti 3 C 2 Cl x MXene heterojunction is synthesized via Lewis acid molten‐salt etching, featuring ultrathin Ni platelets strongly anchored to the MXene substrate through interfacial TiNi 3 bonding. This architecture establishes an S‐scheme charge transfer pathway, as evidenced by in situ irradiated X‐ray photoelectron and X‐ray absorption spectroscopy, which confirm efficient carrier transfer and separation, while femtosecond transient absorption spectroscopy reveals ultrafast interfacial dynamics. Under photothermal conditions, the cooperative interplay of metallic Ni, surface NiO x , and the conductive MXene substrate couples directional charge migration with thermally assisted molecular activation and barrier lowering, thereby enabling regulated CO 2 hydrogenation product distribution between CH 4 and CH 3 OH. Density functional theory demonstrates that surface‐state evolution, rather than simple oxidation degree, modulates adsorption energetics and alters the relative barriers of CH 4 and CH 3 OH pathways, such that moderately oxidized Ni–NiO x interfacial ensembles favour methanol forming intermediates, whereas extensive oxidation suppresses CH 3 OH formation. Collectively, these findings demonstrate a robust strategy for exploiting MXene‐based heterojunction interfaces in photothermal catalysis and underscore the pivotal role of surface state regulated reaction pathways in steering product distribution during CO 2 hydrogenation.

Phonon chirality and Hall effect in Janus materials

Janus materials provide an intrinsic platform for inversion-symmetry breaking and chirality-related phonon phenomena. Here, based on first-principles calculations, we investigate the impact of out-of-plane asymmetry on chiral phonons in Janus SbTeI. We show that exchanging the upper and lower atomic layers produces distinct chirality responses in different structural phases. In the 2H-phase, the phonon chirality in the in-plane directions is reversed while the out-of-plane component is preserved, whereas in the 1T-phase, all three chirality components are simultaneously flipped. We point out that the distinct responses are fundamentally determined by the mirror symmetry Mz and the spatial inversion symmetry P in different phases. Furthermore, these chirality reversals lead to corresponding changes in phonon angular momentum, magnetization under a temperature gradient, and the phonon Hall response in the presence of a magnetic field. Our findings highlight the essential role of Janus asymmetry in phonon chirality and related transport phenomena.

Metal Node Guided Pore Engineering in Carborane‐Based MOFs for Efficient C ₂ H ₂ /CO ₂ and C ₂ H ₂ /C ₂ H ₄ Separations

ABSTRACT The efficient separation of C 2 H 2 from C 2 H 2 /CO 2 and C 2 H 2 /C 2 H 4 mixtures is essential for the preparation of high‐purity C 2 H 2 and C 2 H 4 , but challenged by the trade‐off between the capacity and selectivity. In this work, we report a node guided pore engineering strategy in carborane‐based metal‐organic frameworks (MOFs), leading to the partitioned dual cage system in Co‐CB‐HPBTA in contrast to its analogue Zn‐CB‐HPBTA with one‐dimensional channels. This structural evolution endows Co‐CB‐HPBTA with a high C 2 H 2 adsorption capacity of 103.2 cm 3 /g (4.61 mmol/g) at 298 K and 1 bar, along with superior selectivity for C 2 H 2 /CO 2 (10.6) and C 2 H 2 /C 2 H 4 (13.3). Breakthrough experiments confirm its excellent separation performance for both mixtures under varied conditions, demonstrating efficient recovery of high‐purity C 2 H 2 and C 2 H 4 with remarkable cyclic stability and humidity tolerance. The separation mechanism is elucidated by DFT calculations and in situ single‐crystal‐ray diffraction, which reveal enhanced binding interactions within the partitioned cages through multiple van der Waals contacts, rationalizing the high selectivity.

Pressure-induced emission of dopant-free SU-8 for passive photonic devices

SU-8, a widely used negative-tone photoresist in microelectronics, has low optical loss and excellent processability, making it promising for photonic integrated devices. However, most existing SU-8-based passive photonic devices rely on dye doping to enhance luminescent performance, increasing fabrication complexity. Here, we applied pressure treatment to four types of SU-8 micropatterns prepared by photolithography, which exhibited intense blue-white emission after pressure release and achieved a 15-fold enhancement. This study demonstrates dye-free photoluminescence enhancement in SU-8, providing a new strategy for SU-8-based passive photonic integration.

Harnessing Controlled Dealloying–Support Coupling for Ultrastable PtNi Catalysts in PEMFC Applications

ABSTRACT Platinum–transition metal (PtM) alloys are among the most promising oxygen reduction reaction (ORR) catalysts, yet their practical deployment in proton‐exchange membrane fuel cells (PEMFCs) is hindered by transition‐metal dissolution, particle coarsening, and insufficient durability. Moreover, conventional alloying or intermetallic ordering strategies often aggravate these issues by inducing severe nanoparticle aggregation and instability. Here we report a controllable alloying–dealloying strategy to construct PtNi nanoparticles confined in an N‐doped carbon framework (Pt 1 Ni 1‐x @Ni x _NC). Ammonia‐assisted dealloying produces a Pt‐rich shell with an alloyed core, while the N‐doped carbon anchors the released Ni atoms form Ni–N/C moieties, thereby suppressing agglomeration and strengthening metal–support interactions. This coordination–support coupling optimizes Pt 5d orbital occupation, weakens oxygen adsorption, and accelerates ORR kinetics. Consequently, Pt 1 Ni 1‐x @Ni x _NC exhibits a half‐wave potential of 0.932 V and an ultrahigh mass activity of 2.028 A mgPt −1 , which is 8.75‐fold higher than commercial Pt/C and among the best values reported to date for PtNi‐based catalysts. Remarkably, it shows only a 6 mV half‐wave potential loss after 30,000 cycles, demonstrating exceptional durability. In PEMFCs, the fuel cell delivers 975 mW cm −2 peak power density and retains 91.9% of initial performance, underscoring a generalizable approach for designing durable, high‐performance low‐PGM catalysts for next generation PEMFCs.

Site-selective enhancement of Eu emission in delta-doped GaN

Europium-doped gallium nitride (GaN:Eu) is a promising platform for classical and quantum optoelectronic applications. When grown using organometallic vapor-phase epitaxy, the dominant red emission from Eu exhibits an inhomogeneous photoluminescence (PL) spectrum due to contributions from several nonequivalent incorporation sites that can be distinguished with combined excitation-emission spectroscopy. Energy transfer from the GaN bandgap to the majority site is inefficient, limiting the performance of GaN:Eu light-emitting diodes (LEDs) and resulting in an inhomogeneous emission spectrum dominated by disproportionate contributions from minority sites. In this work, we use site-selective spectroscopy to characterize the photoluminescence properties of delta-doped structures with alternating doped and undoped layers of varying thicknesses and demonstrate that they selectively enhance emission from the majority site when compared to uniformly doped samples. Samples with 2- and 10-nm doped layers show much greater PL intensity per Eu concentration as well as more efficient energy transfer to the majority site, which are both highly desirable for creating power-efficient LEDs. Meanwhile, a sample with 1-nm doped layers shows emission only from the majority site, resulting in a narrow, homogeneous emission spectrum that is desirable for quantum technologies. This utilization of delta-doping has the potential to be broadly applicable for engineering desirable defect properties in rare-earth doped semiconductors.

The Important Role of Carbonyl in Accelerating Reverse Intersystem Crossing for Selenium‐Based Organoboron Narrowband Blue Emitters

ABSTRACT Narrowband emissive polycyclic aromatic heterocycles (PAHs) featuring multiple resonance thermally‐activated delayed fluorescence (MR‐TADF) are capable of achieving high color purity with high exciton utilization efficiency via reverse intersystem crossing (RISC). However, thermally‐activated RISC remains the rate‐limiting step in MR‐TADF molecules due to the typically large singlet and triplet energy gap (Δ E ST ) and weak spin‐orbital coupling. To overcome this challenge, we introduce three carbonyl‐containing organoboron PAHs doped with selenium atoms (pSeXBNO, 1pSeXBN, and pSeXBN) for the first time. Introducing single or dual selenium‐embedded carbonyl heterocycles into the MR core enables significant orbital delocalization of carbonyls, resulting in small Δ E ST and ultrafast RISC rates of 7.5 × 10 6 s −1 for pSeXBNO, 1.5 × 10 7 s −1 for 1pSeXBN, and 4.8 × 10 7 s −1 for pSeXBN. The non‐sensitized OLED employing pSeXBN achieves an emission peak at 478 nm with a narrow bandwidth of 28 nm, along with a maximum external quantum efficiency (EQE) of 32.6% and retaining 28.4% at 1000 cd m −2 , representing state‐of‐the‐art performance for blue MR‐TADF materials. Moreover, bi‐color white OLED employing pSeXBN exhibits excellent performance with a maximum EQE of 30.9% and 23.2% retained at 1000 cd m −2 . These advances demonstrate the role of carbonyl here is of significant guidance in forwarding narrowband blue materials.

Current conduction across multilayer and delaminated MXene Schottky interfaces on <i>n</i> -GaAs and their photoresponse

We report the current conduction across multilayer and delaminated Ti3C2Tx two-dimensional transition metal carbides (MXene)-based Schottky interfaces formed on n-type GaAs. Two types of Ti3C2Tx MXene/n-type GaAs metal–semiconductor (MS) interfaces were created by a simple drop-casting technique using a multilayer MXene coating and a thin film of delaminated MXene. The Schottky barrier heights of the MS interfaces were analyzed from room-temperature as well as temperature-dependent current–voltage (I–V) characteristics across the junction. The Schottky barrier height calculated from the I–V data shows lower values for the delaminated MXene-based Schottky junctions compared to the multilayer-based device. We attribute this difference primarily to reduced Fermi-level pinning at the delaminated Ti3C2Tx/n-GaAs interface and to the presence of a large amount of trapped water in the multilayer Ti3C2Tx structure. The applicability of the rectifying Schottky interfaces as photodiodes was demonstrated as a photodiode at a wavelength of 785 nm. The delaminated MXene-based photodiode shows superior performance with a responsivity of 284 mAW−1 compared to the multilayer MXene-based device.

Efficient Removal of Short‐Chain Perfluoroalkyl Substances by Cavity‐Directed Aggregation in a Molecular Cage Host

ABSTRACT The removal of perfluoroalkyl substances (PFAS) from water is critical to protect human health and the environment. However, removing short‐chain PFAS remains a significant challenge, and a molecular‐level understanding of their binding is lacking. Here, we utilise a metal‐organic cage (MOC 1 ) as a model “pore” to elucidate the host‐guest chemistry of short‐ and long‐chain PFAS in water. X‐ray crystallography of six 1 ·(PFAS) n complexes reveals a broad range of PFAS are encapsulated as anionic aggregates, with the degree of guest‐guest aggregation decreasing as the fluoroalkyl chain length increases. 1 H and 19 F NMR spectroscopy, together with isothermal titration calorimetry reveal the cage host displays unusually large, entropy‐driven association constants in water (log K ≥  5) which remain high for short‐chain PFAS. Doping mesoporous silica 60A with only ∼1 wt% of the cage results in a host‐in‐host adsorbent that removes &gt;98% of short‐ and long‐chain PFAS at environmentally relevant concentrations under flow‐through conditions. The adsorbent exhibits rapid PFAS uptake with high selectivity over common water‐borne anions and full regenerability. These findings translate host‐guest chemistry into an effective materials platform for PFAS remediation, including short‐chain species that evade conventional removal methods.

On the importance of the optical anisotropy in the detection of coherent acoustic phonons in a time-domain Brillouin scattering experiment

In this perspectives paper, we discuss the role of optical anisotropy in detecting coherent acoustic phonons in a time-domain Brillouin experiment. First, we present the general theoretical background to the optical detection of acoustic phonons in a uniaxial material. We then illustrate this theory experimentally by studying highly birefringent BiFeO3 material as a case study. We demonstrate how the amplitude of the time-domain Brillouin signal of both longitudinal and shear phonons can be controlled by selecting the polarization of the probe beam (ordinary or extraordinary). Using classical electrodynamics combined with first-principles calculation of photoelastic coefficients, we find a good qualitative agreement with experiments. Besides the general demonstration of the importance of optical anisotropy, we demonstrate that BiFeO3 exhibits comparable photoelastic coefficients to the technologically significant LiNbO3 and LiTaO3 materials. These findings could lead to the development of BiFeO3-based sub-THz acousto-optic devices. In addition to ferroelectrics, our comprehensive description of the coherent acoustic phonon detection process could, in the future, be extended to other birefringent functional oxides such as TiO2, ZnO, and distorted perovskite systems (ABO3), as well as polar semiconductors such as GaN and two-dimensional and van der Waals materials.

Remote Positioning of Cations Tunes Catalytic Fe‐Mediated Nitrogen Fixation Selectivity for Hydrazine Instead of Ammonia in Protic Media

ABSTRACT Understanding the basis of product selectivity is a central issue in catalyst design. Catalytic nitrogen reduction (N 2 R) provides a salient example; whereas ammonia (NH 3 ) is the common product of N 2 R, hydrazine (N 2 H 4 ) is produced under certain conditions. Using mechanism‐guided design, we report a strategy for tuning redox potential that enables selective reduction of dinitrogen to hydrazine by iron complexes in polar protic media. Incorporation of cationic trimethylammonium (NMe 3 + ) or proton‐responsive dimethylamino (NMe 2 ) groups into a tris(phosphino)borane (P 3 B ) ligand framework affords redox‐tunable iron precatalysts that operate efficiently in methanol. Computational analyses reveal that these ligand modifications anodically shift the reduction potential of an iron hydrazido (Fe═NNH 2 ) intermediate by &gt;400 mV, thereby influencing the key branch point for hydrazine versus ammonia. Critical to success is positioning the cationic charges remote from the Fe–N 2 binding site to preserve the high degree of N 2 activation required for functionalization. Newly prepared tricationic iron complexes, soluble and stable in polar protic media, catalyze N 2 R with N‐fixed yields of up to 73% per reducing equivalent consumed, and with hydrazine selectivity exceeding 20:1 over ammonia. This work highlights the use of remote electrostatic effects to tune multi‐electron catalytic product profiles from a 6e – to a 4e – product.

Imidazolium Cation‐Stabilized Interfacial Chemistry for Durable Aqueous Cadmium‐Iodine Batteries

ABSTRACT Aqueous metal batteries are attractive candidates for large‐scale energy storage owing to their intrinsic safety and low cost. However, their practical application is constrained by dendrite growth, corrosion, and hydrogen evolution reaction (HER), as well as dissolution‐induced parasitic reactions of the cathode materials. Here, we report a durable cadmium‐iodine (Cd//I 2 ) battery enabled by a dual‐interfacial chemistry regulation strategy. The Cd 2+ /Cd redox couple offers moderate potential to suppress HER and strong resistance to acidic and polyiodide corrosion, rendering Cd metal a highly stable anode. Moreover, the incorporation of 1‐butyl‐3‐methylimidazolium cation (BMIM + ) induces preferential adsorption on the Cd anode, forming a functional interphase that lowers local charge density, suppresses dendrite growth, and promotes uniform Cd deposition. At the cathode, strong electrostatic interactions and steric hindrance between BMIM + and polyiodide anions effectively mitigate the shuttle effect. Benefiting from these synergistic effects, the Cd//I 2 battery delivers a high reversible specific capacity of 152.5 mAh g −1 at 10 A g −1 and achieves ultralong cycling stability over 50,000 cycles, with an ultralow per‐cycle capacity decay of 0.00032%. Even under a high I 2 loading of 17.78 mg cm −2 , the battery maintains 400 cycles with high specific capacity of 173.1 mAh g −1 , underscoring its potential for practical application.